(1) Field of the Invention
The present invention relates to a camera system as defined in the preamble claim 1.
(2) Description of the Related Art
Photography was invented in the early part of the 19th century. Fairly soon, silver halides (AgBr, AgCl) were distinguished from the spectrum of light-sensitive materials as they were found to be light-sensitive when dispersed in gelatin. The dispersion was spread on a glass plate, which formed the photosensitive projection surface of the camera. The glass plate was a straight plate, and an optical system was developed which focused the image onto the plate even through apertures larger than a pinprick.
The glass plate was followed by the film, the film was followed by the vidicon, and the vidicon was followed by the digital matrix. However, the image plane still remains a plane both in cameras for still pictures and those for moving pictures. In azimuthal projection, the illumination on the projection surface is proportional to the square of the angle of deflection as measured from the optical axis:I=(L cos4 φ)/4f(1+m)2                 where        I is intensity at image plane,        L is luminance at target,        φ is the angle of a focus-originated radius to the optical axis,        f is the aperture number, and        m is the conversion factor.        
Especially in the case of wide-angle optics, problems are encountered in respect of uniformity of illumination in the image area. Further, wide-angle images with an angular field of the lens exceeding 100° are difficult to accomplish without substantial distortion of straight lines.
In prior art, both of the above-mentioned errors have been corrected by way of digital image processing.
The object of the invention is to eliminate the drawbacks referred to above.